As illustrated in FIG. 5A, a converting circuit 51 having balun is known as an existing converting circuit for converting differential signals to a single-ended signal. In converting circuit 51, a set of differential signals is outputted from input terminal IN and inversion input terminal INX. The input differential signal can be outputted via inductive coupling by coils 52 and 53 as single-ended signal from output terminal OUT.
Further, as illustrated in FIG. 5B, a converting circuit 61 comprising an active element, i.e., transistor, is known as an existing converting circuit for converting differential signals to a single-ended signal. In converting circuit 61, output signal from drain of transistor 63 of one differential amplifier circuit can be outputted as single-ended signal.
Converting circuit 51 having balun does not expend power consumption, and removes common-mode signal noise. However, since balun requires coils 52 and 53, chip area for converting circuit 51 is wide. If converting circuit 51 is a discrete circuit, many components are required to compose converting circuit 51. On the other hand, as illustrated in FIG. 5B, converting circuit 61 having a transistor does not use elements in converting circuit 62. Therefore, half of the power consumption of converting circuit 61 is lost. Further, since only the output signal from drain of transistor 63 is outputted, common-mode signal noise cannot be removed in converting circuit 61.